Please fill in the space inside the skeleton code. it is a question to do calculation by C.

Here are some samples:

> n0? 0 > n8? 0

> n0=2147483648 > n0+3 > n0? 2147483651 > n1=1000000000000000000 > n1+n0 > n1? 1000000002147483651 > n0? 2147483651

#include #include #include #include

#define INT_SIZE 100 /* max number of digits per integer value */ #define LINE_LEN 103 /* maximum length of any input line */ #define NUM_VARS 10 /* number of different huge int "variables" */

#define ASN_OP '=' /* assignment operator */ #define ECH_OP '?' /* echo operator */ #define ADD_OP '+' /* addition operator */ #define MUL_OP '*' /* multiplication operator */ #define POW_OP '^' /* power of operator */

#define OPR1_POS 1 /* position of the first operand */ #define OPR2_POS 3 /* position of the second operand */ #define OP_POS 2 /* position of the operator */

#define CH_ZERO '0' /* character 0 */

#define EXIT_CMD "exit" /* command to exit */ #define PROMPT "> " /* command prompt */ #define CMT_FLAG '%' /* indicator for comment line */

typedef int digit_t; /* a decimal digit */ typedef digit_t huge_t[INT_SIZE]; /* one huge int "variable" */

/* add your constant and type definitions here */

/****************************************************************/

/* function prototypes */ void read_line(char *line, int max_len); void init(huge_t vars[], int lens[]); void echo(huge_t vars[], int lens[], int opr1_index); void assign(huge_t vars[], int lens[], int opr1_index, char *opr2_str); void add(huge_t vars[], int lens[], int opr1_index, char *opr2_str); void multiply(huge_t vars[], int lens[], int opr1_index, char *opr2_str); void power(huge_t vars[], int lens[], int opr1_index, char *opr2_str);

/* add your function prototypes here */

/****************************************************************/

/* main function controls all the action, do NOT modify this function */ int main(int argc, char *argv[]) { char line[LINE_LEN+1]; /* to hold the input line */ huge_t vars[NUM_VARS]; /* to hold 10 huge integers */ int lens[NUM_VARS]; /* to hold the length of the 10 vars */ int opr1_index; /* index of the first operand in command */ char op; /* operator in command */ init(vars, lens); while (1) { printf(PROMPT); /* print prompt */ read_line(line, LINE_LEN); /* read one line of command */

if (line[0] == CMT_FLAG) { /* print comment in the test data */ printf("%s ", line); /* used to simplify marking */ continue; } if (strcmp(line, EXIT_CMD) == 0) { /* see if command is "exit" */ return 0; } opr1_index = line[OPR1_POS] - CH_ZERO;/* first var number at line[1] */ op = line[OP_POS]; /* operator at line[2] */

if (op == ECH_OP) { /* print out the variable */ echo(vars, lens, opr1_index); continue; } /* do the calculation, second operand starts at line[3] */ if (op == ASN_OP) { assign(vars, lens, opr1_index, line+OPR2_POS); } else if (op == ADD_OP) { add(vars, lens, opr1_index, line+OPR2_POS); } else if (op == MUL_OP) { multiply(vars, lens, opr1_index, line+OPR2_POS); } else if (op == POW_OP) { power(vars, lens, opr1_index, line+OPR2_POS); } } /* all done; take some rest */ return 0; }

/* read a line of input into the array passed as argument */ void read_line(char *line, int max_len) { int i = 0, c; while (((c = getchar()) != EOF) && (c != ' ') && (c != ' ')) { if (i < max_len) { line[i++] = c; } else { printf("Invalid input line, toooooooo long. "); exit(0); } } line[i] = '\0'; }

/* print out a huge integer */ void echo(huge_t vars[], int lens[], int opr1_index) { int i; /* print the digits in a reverse order */ for (i = lens[opr1_index]-1; i >= 0; i--) { printf("%d", vars[opr1_index][i]); } printf(" "); }

/****************************************************************/

/* add code below to complete the function bodies, * add more functions where appropriate. */

/* set the vars array to zeros */ void init(huge_t vars[], int lens[]) { int i; for (i = 0; i < 10; i++) { lens[i] = 1; vars[i][0] = 0; } }

/* process the '=' operator */ void assign(huge_t vars[], int lens[], int opr1_index, char *opr2_str) { int i = 0; while ((*opr2_str = getchar()) != EOF) { vars[opr1_index][i] = *opr2_str-48+i; i += 1; } lens[opr1_index] = i; }

/* process the '+' operator */ void add(huge_t vars[], int lens[], int opr1_index, char *opr2_str) { }

/* process the '*' operator */ void multiply(huge_t vars[], int lens[], int opr1_index, char *opr2_str) {

}

/* process the '^' operator */ void power(huge_t vars[], int lens[], int opr1_index, char *opr2_str) {

}